If a sister or friend had plans to steal the boyfriend of Oscar nominee Rachel Griffiths they had better think again.

"I'd prescribe Prosac and get them to see my shrink," said the Australian actress in an interview with BBC World's HARDtalk.

She was talking about the film Hilary and Jackie, for which she has been nominated Best Supporting Actress for the part of cellist Jacqueline Du Pre's older sister.

The controversial film about a young genius who dies of multiple sclerosis, centres on sibling rivalry and Jackie's love affair with her brother-in-law. In the film, sister Hilary allows the affair to continue because of her sister's frail emotional state, something Rachel Griffiths finds difficult to understand.

"I find many human interactions bewildering," she told HARDtalk's Tim Sebastian.

"We are capable of extraordinary self sacrifice for another person, donating organs and going through enormous pain to save a child, you know, all these things, and we're capable of such intense evil to each other as human beings."

But the issues dealt with in Hilary and Jackie also fascinated Ms Griffiths.

"It was a very complex view of humanity," she said. "We're not just good, we inadvertently hurt each other by doing the best we can.

"Love is a complex thing and we get in each others' way, sometimes we do the right thing, sometimes we don't."

Meeting the 'real' Hilary

The film, based on Hilary's own book, has been criticised by several musicians and by critics as a biased and unfair account of Jacqueline Du Pre's life.

But when Rachel Griffiths met Hilary Du Pre after the film was made she said she thought Hilary was "relieved" at the way the story was told.

She said: "I personally wouldn't dare hand over the story of my life to two guys in suits, I'd never met, who'd come to talk me into it.

"She was not there during filming, she didn't approve the scripts, she basically handed over the story and I can't imagine how terrified she must have been when she sat down to see the movie for the first time."

Rachel Griffiths has played supporting roles in films including Muriel's Wedding, My Best Friends Wedding, Among Giants and My Son the Fanatic.

She told HARDtalk she had never expected a film career and has no ambitions to play a leading role.

"I've never wanted to be centre stage, I want to be kind of off-centre," she said.

But if she does get an Oscar on Sunday 21 March she may find herself thrust into the limelight.